WSDL is an XML based format used as a service specification for SOAP services.
A WSDL document defines a service, all the possible requests, the SOAP-Action, Target URLs, Parameters and the used structures. It encapsulates an XML Schema for the structures, parameters and other types. WSDL is a fairly simple format, but by using XML schemas can express everything an XML document can contain.
Remoting SDK supports WSDL and SOAP through the (TRO)SoapMessage classes, allowing consumption and production of SOAP services.